i wouln't get either of them. all ASUS amd motherboards are horrible in comparison with the dfi (just working on history and my experience with my P.O.S A8N-SLI Deluxe) but that dfi has a few gliches. As for OMFGWTFBBQ 2 16X pci-e. IT MAKES NO DIFFERANCE the 7800gtx 512mb don't use that much bandwidth yet :P
also WHY gett 2X7800GTX 512mb????? i mean ull be paying like an extra $800 for a 35% performance gain.
The DFI will overclock better. Some reviewers were very happy with the asus as it hit like 335 fsb but the dfi N-Force4 Ultra-d has been known to hit 400fsb easy
SLI seems like a waste to me but if u feel that u need it then get the dfi